Apparatus for producing phase shift in electronic organs



D. J. LESLIE Dec. 1 1964 APPARATUS FOR PRODUCING PHASE SHIFT INELECTRONIC ORGANS 2 Sheets-Sheet 1 Filed Aug. 28, 1961 INVENTOR. DONHLDZia lEsL/s 1954 D. J. LESLIE 3,159,706

APPARATUS FOR PRODUCING PHASE SHIFT IN ELECTRONIC ORGANS Filed Aug. 28,1961 2 Sheets-Sheet 2 Han Z DOA/HAD C]; 125.94 /E INVEN TOR.

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United States Patent 3,159,7tlt';

APlARATUS FOR PRQBUClNG PHASE SIillFT IN ELECTRUNIQ GRGANS Donald E.Leslie, Electric Music, 56 W. Del Mar Blvd,

Pasadena, Calif. Filed Aug. 28, 1961, Set. No. 134,529

I 10 Claims. (Cl. ltd-1.24)

This invention relates to electronic organs, and particularly to thesimulation of effects produced by natural instruments.

Phase shifts are constantly produced by physical movements of musicalinstruments or accessory apparatus. The human ear cannot sense phase inthe absolute sense; but phase changes are sensed; that is, the carsenses the lrst time derivative of phase. Absence of phase shiftsresults in a certain flatness characteristic of physically fixed soundsources. The phase shifts in natural instruments are not produced inrandom fashion, but in-.

stead in relationship to the progress of the music.

In a pipe organ, the swell shutters not only attenuate sounds emanatingfrom the pipe chambers, but also change the sound radiation pattern,thereby producing the pleasing phase shifts. Phase shifts are constantlyproduced by the swell shutters since they are almost constantly inmotion; the faster the movements of the swell shutters, the greater theeffect on the ear of the listener.

An electronic organ speaker is either physically fixed, resulting in nophase shift, or is rotated at a constant speed, resulting in a regularphase shift unrelated to the progress of the music.

An object of this invention is to provide apparatus for introducingphase shifts in an electronic organ which are clearly related to theprogress of the music. To accomplish this object, use is made of a phaseshift network of suitable design that includes an adjustable or variableelement coupled, mechanically or otherwise, to theswell pedal of theelectronic organ. Phase shift is then introduced upon movement of theswell pedal, and the action of the swell shutters of a conventional pipeorgan is accurately simulated. In other forms of the present invention,use is made of shutters or directional channels operatively associatedwith a speaker mechanically coupledto the swell pedal.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of severalembodiments of the invention. For this purpose, there are shown a fewforms in the drawings accompanying and forming part of the presentspecification. These forms will now be described in detail, illustratingthe general principles of the invention; but it isto be understood thatthis detailed description is not to be taken in a limiting sense, sincethe scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 diagrammatically illustrates a side view of a swell pedal of anelectronic organ together with a variable resistor forming a part of oneembodiment of the present invention;

FIG. 2 is a schematic diagram'illustrating how a variable resistor ofFIG. 1 is used to effect phase shifting;

FIG. 3 is a phase diagram for the circuit of FIG. 2;

FIG. 4 is a diagrammatic side view similar to FIG. 1 but illustrating aswell pedal cooperating with 'a variable inductance device that forms apart of the second embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating how the variable inductancedevice of FIG. 4 is used to accomplish phase shifting;

, indicated by the dotted line position.

FIG. 6 is a diagrammatic exploded view of a third embodiment of thepresent invention;

FIG. 7 is a side view with parts removed, diagrammatically. illustratinga modified form of the present invention;

FIG. 8 is a top plan view of the apparatus shown in FIG. 7; and

FIG. 9 is a'diagrammatic side view with parts removed, illustratingstill another modified form of the present invention. I

InFIG. 2 there is illustrated a phase shifting device 10 interposed inthe circuit for an electric organ signal. The device it) may be locatedat any suitable place, as for example at the pro-amplifier stage.

In the present example, the device 10 includes a re sistance capacitancebridge excited from the secondary 11 of an iron core transformer 12. Thebridge includes two parallel branches, each connected across theexcitation source 11.

One of the branches comprises two serially connected equal resistors 13and 14, and the other branch comprises serially connected capacitor 15and an adjustable resistor 16. A mid terminal 17 is formed betweenresistors 13 and '14, and a mid terminal 18 is formed between capacitor15 and resistor 16. Output leads 19 and 20 extend from mid terminals 17and 18 respectivelytooutput terminals 21 and 22. The succeeding stagecan thus be connected to the device 10. The transformer 12 has a primaryWinding 23 thatis driven by the previous stage appropriately to excitethe resistance-capacitance bridge. The manner in which the phaseshifting device operates can be understood with reference to the phasediagram, FIG. 3.

The phase diagram is a circle diagram in which the voltage across theinputterminals 24 and 25 to the bridge is plotted as the base vector Thevoltage E across the capacitor 15 vectorially added to the voltage Eacross the resistor 16 must, of course, equal the base voltage E.Furthermore, these component voltages E and E must be in relationshipwith respect to each other. end of vector E and corresponding to thebase of vector E, must fall along semi-circular are 27 of which the basevoltage E is the diameter. The actual position along the arc dependsupon the relative impedance values of the capacitor 15 and resistor 16.

Thus as the value of the resistor 16 is reduced, the voltage E movesinto alignment with the base voltage E, as As the value of the resistoris' increased, E diminishes in value, and furbase voltage E.

The voltage at the output terminals 21 and 22 is the voltage at midterminal 18 less the voltage at mid terminal 17. Since resistors 13 and14 are equal, thevoltage of mid terminal 17' is always E/2, and thusrepresented by the mid-point of vector E, which is the center of thecircle diagram.

The voltage at mid terminal 18 is represented in the diagramat thejuncture of vectors E and E,. The output voltage E is then representedby the vector joining points 18and 17 The phase angle of the'vector'Ethus changes from approximately 0 to approximately the am plituderemaining constant. y

In order to adjust the resistor 16, a coupling isestablished to theswell pedal, as shown in FIG. 1. For this purpose, the variable resistor16 is shown as having an operating arm 29 pivotally connected to link 30which in turn pivotally joins a movable portion of the swell pedal 28.The swell pedal 28 in any conventional manner is also operativelyassociated with the circuits of .the organ in order to controlthe'arnplitude' of sound or the intensity Thus the 3 of electricalenergization of a transducer other than a speaker. As the swell pedal 28is depressed, in accordance with the progress of the music, the phaseangle is accordingly changed.

Since ear senses not phase, but change of phase, it will then beapparent that the perceived effect will depend upon the velocity ofmovement of the swell pedal 23.

In the form illustrated in FIGS. 4 and 5, a phase shifting network 31 isillustrated that resembles a three-sectioned low pass filter. However,the cutoff frequency is well above the frequency response of theelectronic organ. The network comprises three serially connectedinductance coils 32, 33 and 34 joining one input terminal 35 to oneoutput terminal 36. Capacitor 47 extends from first inter-coil terminal37 to a common lead 38 joining the other input and output terminals 39and 50. A second capacitor 41 is placed between second inter-coilterminal 42 and common lead 33. A third capacitor extends across outputterminals 36 and ll By following suitable filter design techniques, itis possible, for example, to attain a phase shift the cosine of which isa function of (1KLC)'Wl16I6 K is a frequency related constant, L is theinductance value of the coils and C the capacitance value of capacitors47, 41 and 4-3.

Thus by suitably adjusting the inductance values of the series coils32., 33 and 34, the phase shift may be changed from to 180 correspondingto a change in the cosine function (1-KLC) from +1 to l.

In order to change the value of the inductances 32, 33 and 34, the coilsare wound upon a common frame 44 with respect to which an element 45 ofmagnetic material is movable. In the present example, the element 45comprises a powdered iron core, and it is pivotally connected by a link46 to the swell pedal 23.

Upon movement of the swell pedal 23, the phase shift produced by thedevice 31 is varied substantially between 0 and 180.

By observing suitable design techniques, attenuation can be constant andindependent of frequency throughout the pass band. However, in thisinstance as in the previous form, the phase shift is a function offrequency.

In the form of the invention illustrated in FIG. 6, a variable circuitelement 51 is provided that is connected to a rotary magnet unit 52. Thevariable circuit element 51 may correspond to the adjustable resistor 16or the adjustable impedance coils 32, 33 and 34: of the forms previouslydescribed. The magnet unit 52 has a series of equiangularly disposedpermanent magnets 52a, in this instance, eight in number carried upon acommon support.

The magnets have poles facing inwardly toward'the axis of unit 52, andspaced uniformly therefrom. The polarity of the magnets alternates.Cooperable with the magnets is an armature or drum 53 of magneticmaterial. This drum is mounted for rotation about the axis of the unit52, and the drum completes flux paths between the magnets whereby acoupling is established. The swell pedal 23 imparts mo ion to the drumby the aid of a rack 54 prvotally connected thereto which engages asmall pinion 55 connected to thedrum 53. The arrangement is thus one ofan eddy current brake or clutch, the coupling being established bymagnetic drag. The rack and pinion arrangement causes the drum to rotatethroughout several revolutions upon full depression of the pedal 28.

The magnet device 52 is biased to a central neutral position by the aidof a spring 56. When the swell pedal 28 is moved, a substantial draggingforce is imposed on the magnetic device 52 thereby changing the value ofthe impedance element 51. The motion of the pedal 28 is thus amplifiedso that a slight, but rapid movement of the pedal 28 causes movement ofthe circuit element 51 to its extreme position, where it stays until thepedal 28 decelerates or reverses. A 180 shift then does not de pend uponthe pedal 28 being depressed to the floor. If the swell pedal is slowlymoved, a slight phase shift will be produced since the spring 56 checksthe motion.

Thus, in the present example, changes in phase are produced not inresponse to velocity of the swell pedal 28, but instead in response toits acceleration. Since sudden changes in the swell pedal 28 coincidewith changes in the music, the phase shift introduced correlates withonly pronounced changes in the progress of the music.

In the form illustrated in FIGS. 7 and 8, a speaker 60 is mounted upon aframe 61. The speaker cone registers with an opening 62 provided byframe 61.

In front of the opening 62 are a pair of shutters 63 and 64 pivotallymounted about parallel axes extending parallel to the plane of theopening 62. For this purpose, pivot pins 65 projecting from the rearcorners of the shutters 63 and 64 are journalled in top and bottomflanges 66 in the frame 61.

The shutters 63 and 54 are moved in unison and maintained in parallelrelationship by the aid of pivotally connected linkage parts 67 and aspivotally joined to the swell pedal 69. The shutters channel the soundprimarily by reflection. A change in the length of the sound path inreaching the ear of the listener due to a change in the shutter positionaccomplishes a change in phase. The linkage 67, 68 is so designed andthe shutters are so spaced that the shutters do not significantlyattenuate the sound. The shutters are preferably limited toapproximately a 45 movement on opposite sides of the center, and asindicated by the full and phantom lines in FIG. 8.

The linkage 67, 68 causes the shutters to shift as the swell pedal ismoved, imparting a characteristic phase shift to the music.

In the form illustrated in FIG. 9, a directional sound channel 7i)registers with a speaker '71, and is supported, as by a hearing 72, forangular reciprocation. The sound channel is connected to the swell pedal73 by a crank 74 and rod 75. As the swell pedal 73 is moved, the angularorientation of the directional sound channel shifts angularly and aresult similar to that produced by the shutters of the previous form isobtained.

The inventor claims:

1. In an electronic organ: an organ signal circuit; a phase shiftingdevice interposed in said circuit, and including an element operative toadjust the phase shift produced by said device; a swell pedal; andcoupling means between the swell pedal and said element.

2. The combination as set forth in claim 1 in which said coupling ismagnetic.

3. In an electronic organ: an organ signal circuit; a phase shiftingnetwork interposed in said circuit including a circuit element having avariable impedance operative to change the phase shift produced by saiddevice; said variable impedance having movable actuator means formechanical adjustment thereof; a swell pedal; and a coupling betweensaid swell pedal and said actuator.

4. The combination as set forth in claim 3 together with biasing meansfor determining a normal position of said actuator, and in which saidcoupling comprises magnetic drag members respectively connected to theswell pedal and the actuator.

5. The combination as set forth in claim 3 in which said actuator isbiased to a normal position and in which said coupling is provided by apair of relatively removable magnetic members respectively connected tothe swell pedal and the actuator, one of said members having magnetmeans providing a series of spaced magnet poles, and the other of saidmembers comprising an armature of magnetic material movable relative tosaid magnets.

6. In an electronic organ: an organ signal circuit; an adjustable phaseshifting device interposed in said circuit; a swell pedal; and couplingmeans between the pedal and the device for adjusthig said device tochange the phase at a rate corresponding to the velocity of motion ofsaid pedal.

7. In an electronic organ: an organ signal circuit; an

' adjustable phase shifting device interposed in said circuit;

a swell pedal; and coupling means between the pedal and the device foradjusting said device to change the phase at a rate corresponding to theacceleration of motion of said pedal.

8. The combination as set forth in claim 7 together with means forlimiting the change in phase of said device.

9. In an electronic organ: a speaker; acoustic sound channeling meansregistering with the speaker; means pivotally mounting said soundchanneling means for angular reciprocation; a swell pedal; and a linkagebetween said sound channeling means and said swell pedal; said soundchanneling means having a sound attenuating characteristic substantiallyindependent of its permitted positions.

10. In an electronic organ: an electrical-acoustic transducer; a swellpedal operatively associated with the transducer for controlling theintensity of electrical energize.- tion of said transducer; meansmovable for shifting the phase of the transducer signals; and a linkagebetween the swell pedal and said movable means.

References Cited in'the file of this patent UNITED STATES PATENTS2,114,680 Goldsmith Apr. 19, 1938 2,468,062 Hanert Apr. 26, 194-92,509,923 Hanert May 30, 1950 2,755,695 Krauss et al. July 24, 19562,986,953 De Almond et al June 6, 1961 2,995,054 Leslie Aug. 8, 19613,004,459

Jones Oct. 17, 1961

1. IN AN ELECTRONIC ORGAN: AN ORGAN SIGNAL CIRCUIT; A PHASE SHIFTINGDEVICE INTERPOSED IN SAID CIRCUIT, AND INCLUDING AN ELEMENT OPERATIVE TOADJUST THE PHASE SHIFT PRODUCED BY SAID DEVICE; A SWELL PEDAL; ANDCOUPLING MEANS BETWEEN THE SWELL PEDAL AND SAID ELEMENT.